It has over 1600 chapters already and 166 volumes for crying out loud. Its been running since 1976 and it hasn't stopped. Nothing from the 80s or 90s will beat it. Doraemon and Golgo 13 are older (1969) but they didn't have continues serialization so they lose in chapter count. This is about manga not anime!

http://en.wikipedia.org/wiki/List_of_manga_series_by_volume_count
apperantly it is Kochira Katsushika-ku Kameari Kōen-mae Hashutsujo. it is ongoing and has 170 volumes, and 1613 chapters.
published by Weekly Shonen Jump Shueisha